Impact protection device for rail vehicles

ABSTRACT

The invention relates to an impact protection device for rail vehicles, comprising one or more energy absorbing elements ( 25 ) mounted on the main frame of the rail vehicle and having a box-like structure. The invention is characterized in that from the box end in the direction of the main frame ( 29 ) a reverse-drawn recess ( 20 ) and a buffer rod ( 21 ) are provided and the buffer rod can be displaced along the interior wall of the reverse-drawn recess ( 20 ). Elastically deformable energy absorbing elements ( 32 ) such as a friction spring ( 33 ) or a hydraulic capsule ( 34 ) are mounted in the hollow space formed by the buffer rod ( 21 ) and the reverse-drawn recess ( 20 ). The invention provides a greater active length for energy absorption in case of impact than a sequential box arrangement and a standard sleeve buffer.

FIELD OF THE INVENTION

The present invention relates to a crash guard device for a railvehicle.

BACKGROUND INFORMATION

FIG. 1 of German Patent Application No. 196 35 221.5 shows aconventional crash guard device for rail vehicles.

The device includes energy dissipating elements having a box-shapedstructure and a rectangular cross-sectional shape arranged between themain frame of the rail vehicle and the buffer elements. These energydissipating elements compensate for crash energy that exceeds the energyabsorbing power of the buffer elements. German Patent Application No.196 35 221.5 describes. The embodiment used is characterized in that thecross-sectional shape of the energy dissipating element arranged in eachcase between the buffer element and the main frame in the form of aclosed box-shaped carrier becomes steadily wider in the direction fromthe buffer element to the main frame. The buffer element is a standardbuffer known as a plunger buffer which is known. Such a plunger bufferis composed essentially of a buffer plate 10 mounted on an outside box11 and inverted over an inside part 12, as shown in FIG. 1 of the patentapplication cited above. Outside part 11 and inside part 12 can bedisplaced into one another, and an energy dissipating element, e.g., inthe form of a frictional spring, optionally with an additional hydrauliccapsule, is arranged inside part 12.

A disadvantage of the conventional known crash guard device is that dueto an tandem connection of the conventional energy dissipating elementwith a standard buffer, based on total length L of the crash guarddevice, comparatively little active length is available for absorbingenergy. Of the total length of the standard buffer element, only acomparatively small distance is available for pushing outside part 11over element 12 (distance of travel of the buffer element). In addition,it should be recalled that the full length is not available with theenergy dissipating element, but instead a residual length always remainsin the compressed state.

SUMMARY OF THE INVENTION

According to the present invention a significantly greater active lengthfor absorbing energy is made available with the same total length L.

It should be pointed out here that according to the latest internationalguidelines for the safety of rail vehicles (ERRI B 205/RP1), a minimumuptake energy of 1 MJ is specified for deformation zones. In addition,according to these guidelines, a deformation path of 1 meter should notbe exceeded. However, UIC 566 specifies a minimum strength of 2000 kNfor the structure of the rail vehicle. To absorb the required minimumenergy of 1 MJ with a force level below 2000 kN, a deformation length ofmore than 0.5 meter is necessary. Otherwise, the entire structure of therail vehicle would have to be designed for a higher strength. There areno conventional crash guard devices at the present having a deformationgreater than 0.5 meter.

Through an embodiment of a box-shaped energy dissipating elementaccording to the present invention that has an insertion area and abuffer plunger that fits in it and is inserted into it, the energydissipating element can be designed to be much longer in comparison withconventional devices so that on the whole, a much greater active lengthis available for dissipating energy. To be able to fully utilize thislength, the insertion area must not abut against the main frame when theenergy dissipating element crumples, so the main frame is provided withsuitable recesses.

Advantageous embodiments of the energy dissipation element have agreater stability with respect to lateral forces and torques andeccentric longitudinal forces, torques which deform only through axialbuckling in a crash. This makes use of the finding that when deformationis caused in the box by a crash, the deformation stops first in the areaof the end of the box, where the box has a smaller cross section. Sincethe deformation resistance of the box increases progressively due to theincrease in cross section in the direction of the main frame, buckling,which progresses axially from the end of the box to the main frame,stops so that uncontrolled collapse such as that which could occur witha box having a constant cross-sectional shape can be ruled out. Inanother advantageous embodiment, the box is in the shape of a rectangle,at least in the area of the main frame, with the longer sides beingpositioned horizontally. The lateral supporting forces of the energydissipating element can be increased in this way. To further increasethe lateral supporting forces, lateral reinforcements may be providedaccording to the present invention, also causing a progressive increasein resistance to axial collapse. Thus, this mostly prevents thedeformation from extending to the following structure (main frame). Tofurther ensure a progressively continuous deformation from the end ofthe box to the main frame through axial collapse, the structure of thebox or the energy dissipating element may be provided with weak pointsin defined areas according to the present invention e.g., in the form ofnotches in the wall of the box. These weak points can predetermine whereand in which order the walls of the box are deformed due to parallelsuccessive folding. The defined weaknesses in the structure of the boxare arranged for example, only in the front area of the box or theydecrease toward the rear area in the direction of the main frame. Thestructural measures described here increase safety, so that the box isdeformed only due to axial collapse (compression deformation), which isassociated with a high energy dissipation, but uncontrolled buckling(bending deformation) of the box, which causes only a slight energydissipation can be largely ruled out even with eccentric induction ofthe crash energy.

Yet another embodiment according to the present invention has theparticular advantage that after deformation of the energy dissipatingelement, only the outer box need be replaced, while the insertion areaand the buffer plunger can be reused, optionally as a separate bufferelement.

The present invention will now be explained in greater detail below.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a conventional crash guard device in an uncompressed state(left) and in a compressed state (right).

FIG. 2 shows a first embodiment of a crash guard device according to thepresent invention that has a box-shaped energy dissipating element withan insertion area.

FIG. 3 shows a first embodiment a crash guard device according to thepresent invention that has a box-shaped energy dissipating element and aseparate insertion area.

FIG. 4 shows a first embodiment of a flange for mounting an insertiontube on an energy dissipating element according to the presentinvention.

FIG. 5 shows a second embodiment of a flange for mounting an insertiontube on an energy dissipating element according to the presentinvention.

FIG. 6 shows a true-to-scale comparative diagram of active and inactivelengths of a conventional device (bottom diagram) to a device accordingthe present invention (top diagram).

FIG. 7 shows a table comparing important dimensions of conventionalcrash guard devices to a crash device according to the presentinvention.

FIG. 8 shows a side view of a crash guard device that has anadvantageous design of a crash element.

FIG. 9 shows a cross sectional view in a front area of the crash elementalong line A—A shown in FIG. 8.

FIG. 10 shows a top view of a crash element having a buffer plungeraccording to the present invention.

DETAILED DESCRIPTION

The present invention is described in greater detail below on the basisof embodiments and with reference to FIGS. 2 through 10. An insertionarea and a buffer plunger which is displaceable on the inside wall ofthe insertion area are provided in each case from the end of the box inthe direction of the main frame. Elastically deformable energy absorbingelements, such as a friction spring and/or a hydraulic capsule are builtinto the hollow space formed by the buffer plunger and the insertionarea. Thus, a greater active length is available for energy dissipationin a crash than would be available with a tandem arrangement of a boxand a standard box buffer.

FIG. 2 shows a first embodiment of the crash guard device according tothe present invention. It is made up of a box-like energy dissipatingelement 25, which has an insertion area 20 extending into hollow space24 and is mounted by welds S on a transverse bar 31 of main frame 29.Insertion area 20 accommodates a buffer plunger 21 that has a bufferplate 22. Inside the hollow space formed by the insertion area and thebuffer plunger there is an energy absorbing element 32 having a frictionspring or spring collar 33 and a hydraulic capsule 34. The bottom areaof insertion area 20 and the end face of the end of the box are designedwith reinforcement. Energy dissipating, element 25 is composed of athick plate and for example has a closed, rectangular cross-sectionalshape, with the cross section increasing conically toward the rear tomain frame 29 and being mounted on it with the cross-sectional shape ofa horizontal rectangle. Guide ribs 40, for example applied to top side36 and bottom side 37 as well as side walls 35 by welds S, are providedin hollow space 24. In the event of a collision of the rail vehicle withenergy in excess of the energy absorbing capacity of energy absorbingelement 32, the additional energy is absorbed by deformation of energydissipating element 25. Recess 30 ensures that the total length ofenergy dissipating element 25 can be utilized as a deformable structure,because insertion area 20 can enter this recess 30. Guide ribs 40 ensurethat insertion area 20 passes through recess 30, in particular with aneccentric collision.

FIG. 3 shows a second embodiment of a crash guard device according tothe present invention having a separately arranged insertion area 20(buffer box) to accommodate and guide displaceable buffer plunger 21,whose end is designed as a plate 22 or is provided with a separatebuffer plate. Bottom part 23 of the buffer box may be designed as aplate bottom, for example, depending on requirements, so it isreinforced and optimized in terms of weight. If necessary, the platebottom may be chamfered on the outside. Insertion area 20 that hasbuffer plunger 21 is inserted into hollow space 24 of energy dissipatingelement 25 that has a box-shaped structure and for example a rectangularcross section. To utilize the total length L of the crash guard deviceas optimally as possible and to make available as much active length aspossible, energy dissipating element 25 has a length such that its endsand is attached at the plate end of buffer box 20. Weld joints and/ordetachable connections, e.g., screw connections, may be used to attachbuffer box 20 to energy dissipating element 25. In the embodiment shownin FIG. 3, the plate end of buffer box 20 is designed as a reinforcedpart 26 which has a greater wall thickness than buffer box 20. A flange27 is placed over buffer box 20 and mounted on reinforced end piece 26by a peripheral weld seam. Head piece 28 of deformable energydissipating element 25 has a recess through which the entire bufferelement can be inserted into hollow space 24 of the energy dissipatingelement until flange 27 is in contact with the outer surfaces of headpiece 28. The buffer element then can be screwed onto the energydissipating element. The entire crash guard device is attached by weldsS to main frame 29 or its head part of the rail vehicle. Energydissipating element 25 has a thick plate and a box-shaped structure witha for example closed, rectangular cross-sectional shape. Theadvantageous embodiment of this energy dissipating element is describedin German Patent Application No. 196 35 221.5, i.e., the cross sectionof this energy dissipating element increases conically to the reartoward main frame 29 and is mounted on it with the cross-sectional shapeof a horizontal rectangle. The mount may be in the form of weld seam S;likewise, the connection may be designed to be detachable. Energydissipating element 25 may be provided with connecting plates at theconnection points to main frame 29. In the conically enlarged area,lateral reinforcements in the form of supporting ribs may also beprovided. In the event of a collision of the rail vehicle with an energyexceeding the energy absorbing capacity of the buffer element (20, 21and 22), the additional energy is absorbed by the deformation of energydissipating element 25 as a deformable structure. To be able to utilizethe total length of energy dissipating element 25, a recess 30 isprovided in transverse bar 31 so that the buffer element can passthrough it. The structural design of energy dissipating element 25according to the advantageous embodiment largely ensures that it willnot collapse (bending deformation) even with eccentric induction of theimpact energy but instead will deform by buckling axially. Thisdeformation caused by compression causes a parallel folding of the wallsof energy dissipating element 25 in the manner of a bellows shockabsorber.

With the embodiments illustrated in FIGS. 2 and 3 and explained above,almost all of total length L over which the crash guard device extendscan be utilized as active length. Thus on the whole, one and the samestructure absorbs operating forces while at the same time containing thedeformable structure for absorbing energy. Due to the greater availabledeformation distance, there is a lower force induction into the railvehicle at the same energy dissipation. Thus, the locomotive structurecan have a lighter design and likewise, all the built-in parts can bedesigned for lower shock loads. This yields total overall weightsavings. As an alternative to the embodiment described above, energydissipating element 25 may also be designed in the form of an insertiontube.

FIGS. 4 and 5 show two variants of flange 27 as seen from above. Theflange is reinforced and optimized in terms of weight. The dimensionsultimately depend on the outside diameter of buffer box 20.

FIG. 6 shows a true-to-scale (1:10) diagram comparing a conventionalcrash guard device (bottom) to a crash guard device according to anembodiment of the present invention (top) to permit a direct comparisonof the active and inactive lengths. The most important dimensions of thetwo crash guard devices are also listed in the table in FIG. 7. Thepercentage of the active length (deformation length) of crash element 25has been increased by 72% in comparison with conventional devices. Withregard to the total active length of the crash guard device (deformationlength plus spring stroke) this yields a 56% improvement in comparisonwith conventional devices.

The crash guard device illustrated in FIG. 8 shows an advantageousembodiment of energy dissipating element (crash element) 25. Slightkinks 38 (weak point) are provided in top side 36 and bottom side 37 inthe end area of energy dissipating element 25 facing the buffer plate.First, this reduces the peak force at which deformation of energydissipating element 25 occurs, so that in the event of a collision ofthe rail vehicle with an energy exceeding the energy absorbing capacityof energy absorbing element 32, the rail vehicle is exposed to a lowermaximum force induction. Second, this determines the location of thefirst fold, so that axial collapse is initiated at this location. Thefolding resistance is increased with additional lateral ribbing 39, andan advantageous force-distance curve is predetermined.

FIG. 9 shows the cross section of the crash guard device from FIG. 8along line A—A. Energy dissipating element 25 is designed with U-shapedside walls 35 so that the specified clearances can be maintained. Thus,for example, there is enough clearance (dotted line) for the arrangementof a compressed air tap 42 and its operation. In addition, due to theadvantageous box-shaped design of energy dissipating element 25 with arectangular cross section, which increases conically toward the rear inthe direction of the main frame, it is ensured that the required freepassage 41 beneath the buffer as specified according to theEisenbahnbetriebsordnung [Railway Operating Regulations] (EBO) can bemaintained in the area of the buffer.

FIG. 10 shows a top view of the crash guard device according to thepresent invention. Energy dissipating element 25 has the advantageousbox-shaped design with a rectangular cross section, which is enlargedconically in the direction of the main frame and has U-shaped side walls35. Defined weak points 38, 38′ are provided on top side 36, bottom side37 and side walls 35 to induce axial collapse. Not shown are the partsof the buffer located in the interior of energy dissipating element 25.Only the part of buffer plunger 21 and buffer plate 22 projecting out ofthe insertion area or buffer box 20 is shown here.

List of Reference Numbers

1 main frame

2 transverse bar

3 energy dissipating element (crash element) in the uncompressed state

4 energy dissipating element (crash element) in the compressed state

5, 6 buffer elements composed of

10 buffer plate

11 buffer box

12 inside part of buffer

7 lateral supporting ribs

20 insertion area or buffer box

21 buffer plunger

22 buffer plate

23 bottom part of the buffer box

24 hollow space in the energy dissipating element

25 energy dissipating element (crash element)

26 reinforced end piece of the buffer box

27 flange

28 head piece of the energy dissipating element

29 main frame or head piece

30 recess in transverse bar 31

31 transverse bar

32 energy dissipating element of the buffer

33 friction spring or spring collar

34 hydraulic capsule

35 U-shaped side wall of the crash element

36 top side of the crash element

37 bottom side of the crash element

38 38′ defined weak points

39 ribs to increase resistance to folding

40 guide ribs for the passage of the insertion area through the recessin the transverse bar

41 clearance beneath the buffer (specified by the Railway OperatingRegulations)

42 compressed air tap with operating handle

What is claimed is:
 1. A crash guard device for a rail vehicle,comprising: an energy dissipating element mounted on a main frame of therail vehicle, the energy dissipating element being boxed-shaped andenlarging steadily in the direction of the main frame; and a bufferincluding a buffer plunger having an integrally molded buffer plate, abuffer box and an elastic energy absorbing element arranged between thebuffer plunger and the buffer box, the buffer plunger configured to dipin the buffer box, the buffer box being an insertion area of the energydissipating element and located entirely forward of the main frame, arecess being provided on the main frame for passage of the buffer box sothat the buffer box remains outside of the recess until the energydissipating element collapses toward the main frame and the buffer boxpasses into the recess.
 2. The crash guard device according to claim 1,wherein: the energy dissipating element has a quadrilateralcross-sectional shape.
 3. The crash guard device according to claim 2,wherein: the energy dissipating element has a rectangular cross sectionat least in an area of the mounting on the main frame, the longer sidesof the rectangular cross section being positioned horizontally.
 4. Thecrash guard device according to claim 1, further comprising: lateralreinforcements at least in an area of the mounting on the main frame,the lateral reinforcements arranged to guide the buffer box into therecess upon the energy dissipating element collapsing.
 5. The crashguard device according to claim 4, wherein: the lateral reinforcementsextend over an entire length of the energy dissipating element; and thelateral reinforcements and side walls of the energy dissipating elementform a U-shaped cross section.
 6. The crash guard device according toclaim 4, wherein: the lateral reinforcements and side walls of theenergy dissipating element are each formed in one piece, one of thelateral reinforcements and the side walls being attached to a top partand the other of the lateral reinforcements and the side walls beingattached to a bottom part to form a box-shaped structure.
 7. The crashguard device according to claim 6, wherein: the lateral reinforcementsand the side walls are attached by welding.
 8. The crash guard deviceaccording to claim 1, wherein: the energy dissipating element includesweak points to produce parallel folds extending from an end of theenergy dissipating element to the main frame in the event of acollision.
 9. The crash guard device according to claim 1, wherein: theenergy dissipating element and the buffer box are separate parts, aninverted part of the buffer box being detachably mounted on an end ofthe energy dissipating element.
 10. The crash guard device according toclaim 9, wherein: the inverted part is detachably mounted using screwconnections.
 11. The crash guard device according to claim 9, furthercomprising: a flange welded around the buffer box in the area of an endof the energy dissipating element, the flange being provided formounting the buffer box, the flange being detachably mounted on the endof the dissipating element.
 12. The crash guard device according toclaim 9, wherein: the buffer box and the buffer plunger are bufferelements.
 13. The crash guard device according to claim 1, wherein: thebuffer box has a cylindrical cross section.
 14. The crash guard deviceaccording to claim 4, wherein the lateral reinforcements are in the formof tapered guide ribs.